TRRL RESEARCH REPORT 

About: TRRL RESEARCH REPORT is an academic journal. The journal publishes majorly in the area(s): Public transport & Deregulation. It has an ISSN identifier of 0266-5247. Over the lifetime, 187 publications have been published receiving 1746 citations.

Perceptual abilities of accident involved drivers

Abstract: The report presents an analysis of the visual and perceptual abilities of 370 accident involved drivers in relation to their accident experience. The drivers were volunteers from a group who had been involved in road accidents investigated as part of an in-depth "at-the-scene" study conducted by TRRL. In addition to the results of tests of static and dynamic visual ability, performance tests in a driving simulator and other tests of particular aspects of cognitive performance, data were available for each road user on age, experience, sex, average distance travelled per year and self reported accident histories. The distributions of the various abilities are given in the report, as are the results of correlation and group comparison analyses. A predictive model of accident frequency as a function of age, exposure and some of the "higher order" test results is presented. Once age and exposure had been allowed for, no correlations between accidents and "simple" visual or performance tests could be detected. The implications of the accident model are discussed, and possible directions for future research suggested. (TRRL)

Contram, structure of the model

Abstract: This report describes the basic structure and mechanism of the traffic assignment model contram. The description is relevant for all versions of contram: recent developments in the modelling in contram version 5 are listed briefly. An iterative procedure is used to assign vehicles to their minimum journey time routes through a network taking into account the delay at each junction along a route at the time that a vehicle reaches each junction. The assignment procedure, which uses a packet structure to represent elements of flow of vehicles for movements between origins and destinations, allows multi-routeing for vehicles with freedom of choice of route; fixed route vehicles, such as bases, are sent along their predefined routes, but still encounter the same delays at junctions experienced by other vehicles. The modelling in contram is consistent with the queue calculations in arcady, picady and oscady. Facilities allow for: a full range of junction types; three classes of vehicle; blocking-back between junctions; three options for inputting signal data; fixed route vehicles (eg buses); fuel consumption; banned vehicle movements (without recoding) and 'point-to-point' speeds for comparisons of speeds for selected o-d movements. Recent developments in contram 5 include speed/flow relationships for links, minimum behavioural (or perceived) cost assignment, a more detailed modelling of the effect of linked signals, an improved fuel consumption model, estimation of geometric delay at junctions, a condensed output file for post analysis work, variable and automatic packet sizing, variable saturation flows and capacities for individual time intervals. (TRRL)

'mova': traffic responsive, self-optimising signal control for isolated intersections

Abstract: More than half of the uk's 9000-plus signalised junctions are controlled by independently-operated (uncoordinated) signals with green times varying in response to local traffic flows. Mova (microprocessor optimised vehicle actuation) is the new signal control strategy researched and developed by TRRL for such isolated intersections. Data from vehicle detectors on the junction approaches are analysed by an on-line microprocessor implementing the mova program; the durations of the green signals are controlled by a delay-and-stops minimising logic, or, if any approaches become oversaturated (congested), by a capacity-maximising process. Subject to a final large-scale trial, mova is intended as a general replacement for the gap-seeking, d-system vehicle-actuated (Va) control currently in use. This report describes the mova system, its main principles, the development trials which have taken place, and the assessments of benefits due to mova. It is concluded that mova reduces vehicle delay by an average of about 13 per cent throughout the working day, compared with up-to-date d-system Va; further benefits are likely where, as is often the case, critical Va controller settings (maximum green times) are based on out-of-date traffic data. (a)

The prediction of saturation flows for road junctions controlled by traffic signals

Abstract: DESCRIBES A COMPREHENSIVE PROGRAM OF MEASUREMENT OF SATURATION FLOW AT TRAFFIC SIGNALS AND THE DEVELOPMENT OF PREDICTION FORMULAS WHICH UPDATE THOSE IN: TRAFFIC SIGNALS BY F.V. WEBSTER AND B.M COBBE -- LONDON : HMSO, 1966

Contram 5: an enhanced traffic assignment model

Abstract: CONTRAM 5 is the latest version of the Transport and Road Research Laboratory's traffic assignment program CONTRAM which models time varying traffic demands on urban and other road networks subject to capacity restraint and transient overload, and predicts the variation through time of the resulting routes, queues and delays. CONTRAM 5 contains many improvements to the original modelling and introduces some new facilities. The queues and delay models are compatible with those in the junction analysis programs ARCADY2, PICADY2 and OSCADY. The effects of signal coordination and geometric delay are modelled. Speed/flow relationships, compatible with those in COBA, can be used to represent traffic speeds on high-speed and limited-access roads and to represent the aggregate effect of delays in buffer networks. A revised model is used to estimate fuel consumption and the number of stops at junctions is estimated. The CONTRAM 5 program incorporates improved algorithms for loading and optimum route assignment of traffic and benefits from a major restructuring of the software compared to previous versions of CONTRAM. The need to re-configure the software for different networks is almost completely eliminated by the use of automatic array dimensioning. Methods of predicting memory use and run time have been established. The main text of the Report outlines and discusses the new and modified features of CONTRAM 5, while formal definitions of models and procedures are given in Appendices. This Report is complementary to RR 178 (CONTRAM: structure of the model. Leonard, Gower and Taylor 1989) and describes changes and features specific to CONTRAM 5. (A)